
function howMany(n) {
    let arr = [1]
    arr[0] = 1
    arr[1] = 2
    for (let i = 2; i < n; i++) {
        arr[i] = arr[i - 1] + arr[i - 2]
    }
    return arr[n - 1]
}
console.log(howMany(2))
